One type of alternator for converting mechanical energy to electrical energy in today's vehicles includes a Lundel style rotor. Typically, the Lundel rotor includes two iron claw poles, a field coil winding wrapped onto a plastic bobbin and a shaft extending through the poles and field coil. The rotor is positioned concentrically with a stator. In operation the alternator produces an electrical output through the rotation of the rotor (acting as an electromagnet) relative to the stator. More specifically, an electrical current is induced in a stator winding by a change in the magnetic flux field present between the stator and the rotor.
One well known challenge with the Lundel rotor design is to create a durable method for routing the start and end leads of the field coil. More specifically, the integrity of the attachment of the field coil leads is compromised at high alternator speeds, such as speeds greater than 25000 rpms. While prior art methods for creating field coil lead routings have achieved their intended purpose and perform adequately at lower rpms (20,000 rpm) current routing schemes may not perform adequately at higher rpms. For example, one method requires the use of heat stakes in combination with epoxy and in combination with fan geometry or addition of slip ring geometry to contain the field coil leads. Unfortunately, this method requires excessive packaging space and doesn't provide adequate field coil lead retention at high rotor speeds.
Given that recent trends in the automotive industry have been to increase maximum engine speed requiring improved alternator maximum speed capability, a need exists for an improved alternator rotor which provides enhanced field coil lead retention. This need is further intensified by the additional requirements for increased power which have led to smaller alternator pulleys thus, further increasing the speed of the machine.